This application claims the priority of European Patent Application, Serial No. EP 02 019 333.0, filed Aug. 29, 2002, pursuant to 35 U.S.C. 119(a)-(d), the disclosure of which is incorporated herein by reference.
The present invention relates, in general, to a pencil having an envelope and a writing element received in the envelope.
Normally, a pencil of this type is used to apply color on paper or other flat materials. Other uses of such pencils involve, however, situations in which the writing element, e.g. lead, comes into direct contact with the human skin. Such a pencil may in turn be used, e.g., in a kajal stick or lipstick, for application of color onto the skin, or as a care product for lips, or even for application of a cosmetic or pharmaceutical preparation. When the pencil is intended for direct contact with the skin, particular consideration should be taken as far as skin compatibility is concerned. To prevent undesired skin irritation, care should be taken in the selection of the chemical composition of the writing element of the pencil. In addition, it should be taken into account that the pencil tip remains in a clean, hygienic condition, when contacting the skin.
Contamination of the pencil tip that needs to be cleaned involves macroscopic contamination through granular, smearing or liquid material, such as, e.g., dust, skin particles or hair. When pencils are involved for use in proximity of wounds, cleaning of the pencil tip from invisible, especially microbial contamination is of particular importance. Contamination of this type relates, e.g., to an attack of the pencil tip by bacteria, viruses, mites or fungi. Since the medical or pharmaceutical field requires compliance with a very stringent hygienic standard, disposable materials, such as gloves, syringes, applicators, and the like, are normally used for administration of drugs or for carrying out therapeutic procedures, or materials are employed, such as suitable metals or plastics, which can be cleaned rapidly and thoroughly. In these areas, the use of pencils, in particular soft-core pencils, is generally not considered an option, even though their usage would be desirable in view of their easily handling.
It would therefore be desirable and advantageous to provide an improved pencil which obviates prior art shortcomings and which is constructed for use in the medical or pharmaceutical field.
According to one aspect of the present invention, a pencil includes a writing element; an envelope arranged in surrounding relationship to the writing element and defining with the writing element a pencil tip, and a cleansing material combined with the envelope for effecting a spontaneous cleaning of the pencil tip.
To ensure clarity, it is necessary to establish the definition of several important terms and expressions that will be used throughout this disclosure. The term xe2x80x9cenvelopexe2x80x9d relates to all pencil components which are disposed permanently or temporarily in immediate adjacent relationship to the writing element, such as a barrel arranged in surrounding coaxial relationship to the writing element, or an optional cap placed over the end of the pencil for protection. The term xe2x80x9ccleansing materialxe2x80x9d refers to any cleansing agent that is capable to eliminate macroscopic and/or microbial contamination. The terms xe2x80x9cself-cleaningxe2x80x9d or xe2x80x9cautomatic cleaningxe2x80x9d or xe2x80x9cspontaneous cleaningxe2x80x9d are used interchangeably and are meant to refer to a cleaning action, with or without requirement for the application of external influence, to prevent the adherence of dirt or contamination as a result of the use of the cleansing material. In other words, contamination is prevented from occurring in the first place, or the contamination is eliminated as a consequence of the effect of the cleansing material, when the pencil is used, e.g. during sharpening, without necessitating a separate cleaning process of the pencil tip.
The present invention resolves prior art problems by providing the pencil with a self-cleaning action by integrating the cleaning material in the pencil. Thus, the need for a separate cleaning agent, which has to be stored separately, is eliminated. A pencil according to the present invention is thus useable for a wide variety of applications, and may be handled also by unskilled personnel without risk. Use of the novel and inventive pencil is not only possible in a clean environment as encountered in hospitals but even when exposed to unhygienic circumstances, e.g. during travel.
According to another feature of the present invention, the cleansing material is a passively cleaning substance. A passively cleaning substance involves an agent that exhibits repellency to contaminants. There are many such materials at the disposal of an artisan, which primarily repel macroscopic contamination. Examples include the use of a so-called anti-stick surface, as widely used, for example, in conjunction with kitchen utensils, and involves the provision of a smooth, tense surface structure, a chemical inertness and thus a very low friction coefficient, to thereby prevent macroscopic contaminants from adhering to the surface. A particular useful material is polytetrafluoroethylene (PTFE), which is chemically and biologically inert as well as hydrophobic and is commercially available under the name Teflon. Suitably, the envelope of the writing element may be lined with a PTFE coating, or the envelope may be made entirely of PTFE, and may be made of a composite material which contains PTFE.
According to another feature of the present invention, the envelope may have a non-wetting surface at least in an area of the pencil tip to thereby realize a repulsion of macroscopic contamination. The xe2x80x9cnon-wettingxe2x80x9d effect of a surface is often referred to a xe2x80x9clotus effectxe2x80x9d and manifests itself by the characteristic that liquids, such as water, will not adhere to the surface but rather trickle down. The lotus effect is realized by a surface which has a microscopic fine texture, e.g. in form of small naps. Thus, water as well as other contaminations contact the surface only in an area of the nap ends, i.e. only in a very small area and thus are unable to stick to the surface.
The provision of an anti-stick surface as well as a non-wetting surface prevents a deposit of macroscopic contamination. A macroscopically clean surface is, however, also suitably to inhibit a deposit of a microbial contamination, because germs can neither adhere nor grow on a clean surface. The provision of a passive cleaning action is also advantageous because no toxic or irritating agent is released so long as the pencil is used as intended. Thus, the pencil is highly compatible, especially when handled by allergic people.
According to another feature of the present invention, the cleansing material may have an actively cleaning effect, in addition or as an alternative to the passive cleaning action. An active cleaning effect relates primarily to microbial contamination and refers to a chemical agent that is toxic to or decomposes germs or fungi. An example of an active cleaning action of the writing element involves the manufacture of the envelope with a plastic that by itself has antimicrobial properties. Plastics of this type may include a polymer containing a disinfectant. Examples of suitable polymers with antimicrobial effect include those commercially available under the trademarks SAM-Polymers(copyright) or AMINA(copyright) and distributed by Creavis GmbH, Germany.
Depending of the particular application at hand, in particular on the active ingredient contained in the writing element as well as on the utilized cleansing material, there are many ways to integrate the cleansing material in the envelope. For example, in situations when the cleansing material has undesired side effects, it may be suitable to add the cleansing material as a permanent component to the envelope either in the form of a coating applied to the envelope, or spread throughout the entire envelope. In this way, contaminants are prevented from sticking in proximity of the writing element, while the cleansing material is prevented from migrating into the material of the writing element itself and thus from reaching a person""s skin. An example of a suitable coating involves a coating on the basis of polyammonium salts.
When using a cleansing material that poses no health hazard and is safe to the environment, it may be suitable to formulate the cleansing material as a migrating component of the envelope material. In other words, the envelope material may contain a component which may be gaseous or liquid and escapes slowly over a long period from the envelope material As a result, the writing element is constantly exposed to discharged cleansing material, e.g., with antimicrobial effect, and thus can also be kept clean during storage.
According to another feature of the present invention, the cleansing material may be a component which is captivated in the material of the envelope and released only, when the envelope is subject to a mechanical load. This is suitable in those situations when the ejection of cleansing material is triggered by external influence, e.g., application of a mechanical force on the envelope during intended use of the pencil, e.g. during sharpening of the pencil or during a movement of the writing element relative to the envelope. In these situations, cleansing material is discharged only when the pencil is used. A targeted discharge of the cleansing material is very economical, especially during storage times, when no cleansing material is spent. Yet, a thorough cleaning of the pencil tip is realized whenever the pencil is in use. This concept can be implemented, for example, when the envelope contains a microporous carrier substance having pores for receiving the cleansing material. So long as the pores are closed, loss or aging of the cleansing material trapped in the pores is effectively countered. Only when the pores are opened, for example, upon sharpening of the pencil and accompanying cutting of the pores, is the cleansing material able to issue out and to wet the pencil tip to effect the cleaning action. Cleaning may hereby be implemented actively by killing germs, or passively, as the cleansing material forms a contamination-repellent film about the pencil tip.
There are innumerable ways of structuring a pencil according to the present invention, only several of which will be detailed here. However, other embodiments which generally follow the concepts outlined here are considered to be covered by this disclosure. Basically, the principal construction of the pencil will depend on the application at hand, i.a. also on the hardness of the used lead.
According to another feature of the present invention, the pencil may configured in the form of a lead pencil, whereby the envelope is a barrel, with the barrel and the writing element disposed in fixed surrounding coaxial relationship. The barrel may be made of wood composite or plastic. Pencils of this type can easily be sharpened as the barrel provides support and protection. During sharpening, material is removed from the old surface of the pencil tip, soiled during storage and use. The cleansing material assumes here primarily the function of preventing a renewed contamination of the exposed surface when touching a sharpening tool or contacting a person""s skin.
As an alternative, the barrel and the writing element may be disposed in surrounding coaxial relationship, with the writing element being moveable relative to the barrel. This construction is suitable for pencils that include a very soft and broad writing element. Suitably, the movement of the writing element is implemented by an advancing mechanism, e.g. a rotary drive, which is generally known from lipsticks and received in the envelope to advance the writing element when applying a rotation movement. The advancing mechanism may also be configured in analogy to a retractable pencil in the form of a pressure-activated drive to advance the lead. A specific construction and manner in which a pressure-activated advancing mechanism can be operatively and functionally incorporated into the pencil of the present invention is fully described, for example, in published U.S. patent application Ser. No. 20010014248, published Aug. 16. 2001. This configuration is suitable when the pencil is provided with an exchangeable writing element. The pencil may also be configured in the form of a so-called xe2x80x9cliquid linerxe2x80x9d, which involves the provision of a writing element in the form of a viscous or liquid fluid retained in the envelope. In this construction, the envelope includes a discharge member, e.g. a brush, ball or foam element, at the pencil tip for discharge of the writing element in controlled doses.
According to another feature of the present invention, the envelope may be lined with an impervious coating in the form of a lacquer to protect the envelope against the outside. This construction is suitable when the cleansing material migrates because the protective coating not only prevents ingress of contaminations into the envelope but also a wasteful escape of cleansing material to the outside.
According to another feature of the present invention, the cleansing material may be provided only in proximity of the pencil tip. In this way, the writing element and the contained active ingredient is exposed to the action of the cleansing material only shortly before use. Undesired long-term reactions of the active ingredient, contained in the writing element, and the cleansing material are thereby effectively precluded.
A pencil according to the present invention is suitable for use with a writing element which contains a medical or pharmaceutical active ingredient, because the integration of the cleansing material satisfies the hygienic standards without requiring additional external measures. The cleaning action of the pencil can be optimized, when the cleansing material is a combination of afore-stated formulations and, optionally, applied at different location. For example, it may be possible, to construct the envelope of several layers, with the outer layer exhibiting a passive cleaning action, while the inner layer is used for an active cleaning of the writing element. As an alternative, it may also be possible, to provide the cap and the barrel with different cleansing material. It is also conceivable to configure a pressure-activated drive for advance of the writing element in a manner that the barrel material is exposed to mechanical force at the same time as the writing element is advanced, so that the advance of the writing element is accompanied by a controlled discharge of cleansing material.